This invention relates to articles which require wear-resistance, such as components used in turbine engines. In some specific embodiments, it relates to improved techniques for applying such coatings to surfaces that are difficult to access.
Components are used in a wide variety of industrial applications, under a diverse set of operating conditions. In many cases, the components are provided with coatings which impart various characteristics, such as corrosion resistance, heat resistance, oxidation resistance, and wear resistance. As an example, the various components of turbine engines are often coated with thermal barrier coatings, to effectively increase the temperature at which they can operate.
The wear-resistant coatings (often referred to as "Wear coatings") are frequently used on turbine engine components, such as nozzle wear pads and dovetail interlocks. The coatings provide protection in areas where components may rub against each other, since the rubbing--especially high frequency rubbing--can erode the part. Various coatings may be used for this purpose, e.g., chromium carbide or cobalt-molybdenum-chromium-silicon coatings. The coatings are usually applied by thermal spray techniques, such as air plasma spray (APS), high velocity oxy-fuel (HVOF), and vacuum plasma spray (VPS).
The thermal spray techniques are quite suitable for applying wear coatings to many substrates. However, they are sometimes not effective for applying the coatings to regions of a substrate which are somewhat inaccessible, since the spray equipment may be too large and cumbersome for such regions. For example, it can be very difficult to thermally spray a wear coating on a flange or other surface of a turbine engine part. Moreover, the spray process, which may include one or more masking steps, is sometimes very time-consuming. Thus, new methods for efficiently applying wear coatings to inaccessible regions of a substrate would be welcome in the art.